HomeMy WebLinkAbout921549.tiff B 1323 REC 02275058 01/14/92 11 : 37 $0 . 00 1/002
F 0078 MARY ANN FEUERSTEIN CLERK & RECORDER WELD CO, CO
AR22?5056
ORDINANCE NO. 89-V
IN THE MATTER OF THE REPEAL AND RE-ENACTMENT, WITH AMENDMENTS OF CERTAIN
SECTIONS, AND THE ADDITION OF CERTAIN SECTIONS TO ORDINANCE NO. 89, WELD COUNTY
ZONING ORDINANCE, AS CURRENTLY AMENDED, REVISING AND ADDING CERTAIN PROCEDURES,
TERMS, AND REQUIREMENTS
BE IT ORDAINED BY THE BOARD OF COUNTY COMMISSIONERS OF WELD COUNTY, COLORADO:
WHEREAS, the Board of County Commissioners of Weld County, Colorado,
pursuant to Colorado statute and the Weld County Home Rule Charter, is vested
with the authority of administering the affairs of Weld County, Colorado, and
WHEREAS, the Board of County Commissioners has the power and authority
under the Weld County Home Rule Charter and State Statute, including Article 28
of Title 30, CRS, to adopt zoning regulations for the unincorporated areas of the
County of Weld, and
WHEREAS, the Board of County Commissioners of Weld County, Colorado, has
previously adopted Ordinance No. 89, Weld County Zoning Ordinance, establishing
a comprehensive revision of the zoning regulations and zoning maps for
unincorporated areas of the County of Weld, and has adopted amendments in
Ordinances No. 89-A through 89-U, and
WHEREAS, said Ordinance No. 89, as amended, is in need of revision and
clarification with regard to procedures, terms, and requirements therein.
NOW, THEREFORE, BE IT ORDAINED by the Board of County Commissioners of Weld
County, Colorado, that certain existing sections of said Ordinance No. 89, as
amended, are repealed and re-enacted, with amendments, and the various sections
are added or revised to read as follows:
Amend Section 53.4. 1 and 53.4.2 by changing "September 28, 1990" to
"September 27, 1991" in the text.
Repeal the Flood Insurance Study for Weld County revised September
28, 1990, prepared by the Federal Emergency Management Agency.
Adopt by reference the Flood Insurance Study for Weld County,
revised September 27, 1991, prepared by the Federal Emergency
Management Agency.
Repeal the Weld County Flood Hazard Overlay District Zoning Maps
that are the Flood Insurance Rate Maps (FIRM) Panel Numbers 080266
0605A, 080266 0608A, the Map Index 080266 0001 1075, and the
Floodway Map Panel Number 080266 0001.
Adopt by reference new Weld County Flood Hazard Overlay District
Zoning maps that are the Flood Insurance Rate Maps (FIRM) Panel
Numbers 080266 0605D, 080266 0608D, and the Map Index 080266 0001
1075. All maps were revised September 27, 1991, by the Federal
Emergency Management Agency.
921549
o,ab q v Cc. - P)-
B 1323 REC 02275058 01/14/92 11 : 37 $0 . 00 2/002
F 0079 MARY ANN FEUERSTEIN CLERK & RECORDER WELD CO, CO
Page 2
RE: ORDINANCE 89-V - ZONING
Adopt by reference a new Weld County Flood Hazard Overlay District
Zoning map that is the Floodway Map Panel Number 080266 0001 revised
September 27, 1991, by the Federal Emergency Management Agency.
If any section, subsection, paragraph, sentence, clause or phrase of this
ordinance is for any reason held or decided to be invalid or unconstitutional,
such decision shall not affect the validity of the remaining portion. The Board
of County Commissioners hereby declares that it would have passed the ordinance,
and each phrase thereof irrespective of the fact that any one or more sections,
subsections, paragraphs, sentences, clauses, or phrases might be declared to be
unconstitutional and invalid.
The above and foregoing Ordinance No 89-V was, on motion duly made and
seconded, adopted// /, by the following vote on the 13th day of January, A.D. , 1992.
/01 ///'1 (/GG/ BOARD OF COUNTY COMMISSIONERS
ATTEST: &''//" WELD COUNTY, COLORADO
Weld County Clerk to the Board
/ G or a Kennedy, Chairman
Deputy Clerk o the Board _ Conee;e7L. -$I�rhe t, ro-Tem
I
APPROVED AS , 'FORM /
f ` ' C. W. Ki
C &��� -r� ((%% �Y
County Attorney Gord
141 "AlLeliz)Pi
IC
W. H. ebste
FIRST READING: December 11, 1991
PUBLICATION: December 19, 1991
SECOND READING: December 30, 1991
PUBLICATION: January 3, 1992
FINAL READING: January 13, 1992
PUBLICATION: January 16, 1992
Effective date: January 21, 1992
HEARING CERTIFICATION
DOCKET NO. 91-57
RE: REPEAL AND RE-ENACTMENT, WITH AMENDMENTS OF CERTAIN SECTIONS, AND
ADDITION OF CERTAIN SECTIONS TO ORDINANCE NO. 89, WELD COUNTY ZONING
ORDINANCE, AS CURRENTLY AMENDED, REVISING AND ADDING CERTAIN
PROCEDURES, TERMS, AND REQUIREMENTS
A public hearing was conducted on December 11, 1991, at 10:00 A.M. , with
the following present:
Commissioner Gordon E. Lacy, Chairman
Commissioner George Kennedy, Pro-Tem
Commissioner Constance L. Harbert
Commissioner C. W. Kirby
Commissioner W. H. Webster
Also present:
Acting Clerk to the Board, Shelly Miller
Assistant County Attorney, Lee Morrison
Planning Department representative, Lanell Swanson
The following business was transacted:
I hereby certify that pursuant to a notice dated October 21, 1991, and
duly published October 24, 1991, in The New News, a public hearing was
conducted to consider amendments to the Weld County Zoning Ordinance
concerning Sections 53.4. 1 and 53.4.2, the Flood Insurance Study for Weld
County, and the Weld County Flood Hazard Overlay District Zoning Maps.
Lanell Swanson, Planning Department representative, made this matter of
record and read the favorable recommendation of the Planning Commission.
Ms. Swanson said this deals mainly with the flood insurance rate maps, and
she read Ordinance 89-V into the record. There was no public testimony
concerning this matter. Commissioner Kennedy moved to approve Ordinance
No. 89-V on first reading. The motion was seconded by Commissioner
Webster, and carried unanimously.
This Certification was approved on the 16th day of December, 1991.
1// //1 /A /� APPROVED:
ATTEST: /it/ 17) _// _ BOARD OF COUNTY COMMISSIONERS
�� a // ✓( 6 ��������( WELD CO TY COLORADO
Weld County Clerk to /the Board
By: /, Go L y, airman
KtyheBo
a
Ge ge Ke edy, ro-Tem
TAPE #91-35
Constance L. Hafbert
DOCKET #91-57
C. W. Kirby
�/� i
ORD89V / i j i �-- ,
W. H. Weebsttee}/ (� 9Yf /
�_c ', rim
t ELD C0V',TY
SNIMITENTEEN OF COQ,. . 'FRS ���nB.g.r,ANf1 ADDITIOSECTIONS N CF .
STATE OF COLORADO 1992 !� 26 EA 22 gEaTniANCE No. A WEE
IG.G. i� An 9: codtrEN3 A OIN ZONING GEND�D
COUNTY OF WELD REVISNG P AND TE "N°
CLERK
BE oRD :9"MBy T1�Bonne
BOARD
CF m1mmTY COMMISSIONERS of
David S. Reynolds, being duly sworn,TO THE �� comma �
Gaye that he is B a wed
publisher of awa¢�1drmt
The New News, a weekly newspaper �isv4 the
Hama Ft
ot
published in Keenesburg in said CountyCala e° i°tes ga sae1d
and State; that said newspaper has a dS 1e Board r Cow
Cmm armere hay thenaposwdyer and
general circulation in said County wrd gee
ithi haver and state tata a
the
and has been eontinously and iadmanmsesofThe ,
uninterruptedly . published therein, adopt k�oniine�gg regdanoeea for
mbemprated rrr� r the seedy r
during a period of at least the Hoed of County
'fifty—two consecutive weeks prior to Commissioners of Weld Coentr
the first publication of the annexed cvlaado, has previously adopted
oOllaellOe rdinance,Na 80.dab hang ��a notice; that said newspaper is azoning bg
newspaper within the meaning of the nee and g maps for
aar�eaead Bier d a
act of the General Assembly of the w0 t�9a aDlnaagb" and
State of Colorado,, entitled "An Act said in need c ° e9
to regulate the _ with r regard r,printing of legal em and reams ents_k ru
notices and advertisements, " and pFD
amendments thereto; that the notice Camn�tm rs
of which the annexed is a printed and ret�With
alrlanthella copy taken from said newspaper, wasaaaed & ta r
way, to
published in said newspaper, and infollows: MA2 V/
sr 2 the regular and entire issue of 11 UM"� the'�
every number thereof , ne Flaad bees ce
Slie
e.V2t•1 p�-1.ef 7�p,�prered bYred eien
once 4r week for 3 - Flood
Emerge�Itudy' a�7wg9a]ld�coanty
successive weeks; that said notice TemersePtaiiin the puler.
Emperge"n�
Wish: so published in said' newspaper n1neped Ink FMte�nde
proper and not in any supplement dHared Flood Insurance Raze
thereof , and that the first tea) Panel NumbersWa OMB
aamt amen, the
erence new Weld
publication of said notice as Pr
ood
aforesaid, was on thenum Flood Zoning d°'`m�bayppara
Insurance
Re<e �: (FBiM)Pane
Numbers OM r,+r m0�6 aoh,
day of Y QC. . -, to q_a AIL a mthepyMaPwee al D
Mai a the Federal mere gency
a rrew W c'aadva land and the last on the 1 L day of ply rep
feet ey the F00M revised Ma Panel
Number MOB a reused
, 19 If 19x1, tN des Federaalktic MI mycia,.......Hy0
Nimmmt
If phrase' el [tor a 1xe Ls fa are' rn.m held a
decided to be invalid or
arh�d�alv'm yea
Subscribed and sworn to before g fare9Pe ve Ce
ll fact
alai °e aaone01ebe"ad deeed
me this .day of $1'12tek , ;btu, pa gr
19 o C11 Yy Orpas,on d, �i°°tla�y"me togo �glade voe�te
�//�� o r np 7th January,AD.,1992
firCountypanalaglaratirrusid
IMISOlit• C.W.KSty PS TD FDNU:
ww.Webster
'[lure.a David Cwac nmaey--
FIRST READING:December 11.1991
PCBLICASECOND READING: 31,
My Cormnlssion Expires March 15, 1995 •
NOTICE OF PUBLIC HEARING
Docket No. 91-57
The Board of County Commissioners of Weld County, Colorado, will conduct a public
hearing at 10:00 A.M. , on Wednesday, December 4, 1991, in the Chambers of the
Board of County Commissioners of Weld County, Colorado, Weld County Centennial
Center, 916 10th Street, First Floor, Greeley, Colorado, for the purpose of
considering amendments to the Weld County Zoning Ordinance as summarized below:
Amend Section 53.4. 1 and 53.4.2 by changing "September 28, 1990" to
"Revised September 27, 1991" in the text.
Repeal the Flood Insurance Study for Weld revised September 28,
1990, prepared by the Federal Emergency Management Agency.
Adopt by reference the Flood Insurance Study for Weld County,
revised September 27, 1991, prepared by the Federal Emergency
Management Agency.
Repeal the Weld County Flood Hazard Overlay District Zoning Maps
that are the Flood Insurance Rate Maps (FIRM) Panel Numbers 080266
0605A, 080266 0608A, the Map Index 080266-0001-1075, and the
Floodway Map Panel Number 080266 0001.
Adopt by reference new Weld County Flood Hazard Overlay District
Zoning maps that are the Flood Insurance Rate Maps (FIRM) Panel
Numbers 080266 0605D, 080266 0608D, and the Map Index 080266 0001
1075. All maps were revised September 27, 1991, by the Federal
Emergency Management Agency.
Adopt by reference a new Weld County Flood Hazard Overlay District
Zoning map that is the Floodway Map Panel Number 080266 0001 revised
September 27, 1991, by the Federal Emergency Management Agency.
All persons in any manner interested in the proposed amendments to the Weld
County Zoning Ordinance are requested to attend and may be heard.
Materials pertaining to the proposed amendments are available for public
inspection in the office of the Clerk to the Board of County Commissioners,
located in the Weld County Centennial Center, 915 10 Street, Third Floor,
Greeley, Colorado, Monday through Friday, 8:00 A.M. to 5:00 P.M.
BOARD OF COUNTY COMMISSIONERS
WELD COUNTY, COLORADO
BY: DONALD D. WARDEN
WELD COUNTY CLERK TO THE BOARD
BY: Shelly Miller, Deputy
DATED: October 21, 1991
PUBLISHED: October 24, 1991, in The New News
NOTICE OF CHANGE OF HEARING DATES
Public hearings, previously scheduled for December 4, 1991, will be held
in the Chambers of the Board of County Commissioners of Weld County,
Colorado, Weld County Centennial Center, 915 10th Street, First Floor,
Greeley, Colorado, on December 11, 1991, at the times specified. All
persons in any manner interested in the hearings are requested to attend
and may be heard.
Probable Cause Hearing - Oakley (cont from 10/02/91) 9:00 AM
Convene as Windsor Shores Law Enforcement Authority 9:00 AM
Show Cause Hearing - Columbine Iron and Metal, c/o Philippe
(cont from 06/26/91) 10:00 AM
Ordinance 89-V - Zoning Ordinance Amendments 10:00 AM
BOARD OF COUNTY COMMISSIONERS
WELD COUNTY, COLORADO
BY: DONALD D. WARDEN
WELD COUNTY CLERK TO THE BOARD
BY: Shelly Miller
Deputy Clerk to the Board
DATED: November 18, 1991
PUBLISHED: November 21, 1991 in The New News
CPI) (49V
•
STATE OF COLORADO
)s.s.
COUNTY OF WELD
David 8. Reynolds, being duly sworn,
says that he is publisher of
The New News, a weekly newspaper
published in Keenesburg in said County
and State; that said newspaper has a
general circulation in said County
and has been continously and
uninterruptedly published therein,
curing a period of at least
'fifty-two consecutive weeks prior to
the first publication of the annexed NOTICE OF CHANGE OF
notice; tat said newspaper is a HEARING DATES
h
newspaper •within the meaning of the Public hearings, previously
act of the General Assembly of the scheduled for December 4,
State of Colorado,, entitled "An Act 1991, will be held in the
Chambers of the Board of
to regulate the printing of legal County Commissioners of
notices and advertisements, " and Weld County, Colorado, li
Weld County Centennial
amendments thereto; that the notice Center, 915 10th Street, First
Floor, Greeley, Colorado, on
of which the annexed is a printed December 11, 1991, at
the
copy taken from said newspaper, was time specified. All persons in
ti any manner interested in the
published in said newspaper, and in hearings are requested to
the regular and entire issue of attend and may be heard.
Probable Cause Hearing -
every number thereof , Oakley front from 16/02/91)
9:00 a.m.
Convene as Windsor Shores
once a week for Law Enformcement Authority
successive weeks; that said notice ho
S a.m.
Show Cause Hearing
was so published in said newspaper Columbine Iron and Metal,
proper and not in any supplement co Philippe front from
06/26/91) 10:00 a.m.
thereof , and that the first , Ordinance 89-V Zoning
publication of said notice as Ordinance Amendments 10:00
a.m.
aforesaid, was on the BOARD OF COUNTY
COMMISSIONERS
WELD COUNTY, COLORADO
at day of -, 19 C��, BY: DONALD D. WARDEN
WELD COUNTY CLERK
TO THE BOARD
and the last on the 2^1 day of Deputy Clerkytohthe MiBolanr
d
\, DATED: November 18, 1991
1 w 9 y. f PUBLISHED: November 21,
1991 in The New News
Subscribed and sworn, to before
za
me this alv day of
19 .
My Commission expires Mart"i r, 1009
mEmoRAnDu
NoeTo Board Date November 18, 1991
COLORADO From Clerk to the Board's Office
Subject: December 4, 1991 Hearings
Due to the Board being scheduled to be at CCI on December 4, 1991, the
hearings set for that date need to be rescheduled. If you have no
objections, we recommend the following hearings be rescheduled to December
11, 1991, at the following times:
Probable Cause Hearing - Oakley (cont from 10/02/91) 9:00 AM
Convene as Windsor Shores Law Enforcement Authority 9:00 AM
Show Cause Hearing - Columbine Iron and Metal, c/o Philippe
(cont from 06/26/91) 10:00 AM
Ordinance 89-V - Zoning Ordinance Amendments 10:00 AM
COI'
} � ? r. i 1t
. '
��.
STATE OF COLORADO )
TO ,ti_. .,
)s.s. .,:
COUNTY OF WELD )
NOTICE OF PUBLIC HEARING
David S. Reynolds, being duly sworn, Docket No.91-57
says that he is publisher of The Board of County
Coorado, ners of Weld Cpubly,
The New News, a weekly newspaper Colorado, will conduct a public
hearing at emb a.m. in
published in Keenesburg in said CountyttheaChamb rs of er van,
and State; that said newspaper has a Co Chambers of me Roam of
County C olorad iobere of Wnld
General circulation in said County Cenntn, Colenteo, Weld CountS
Centennial Center, 915 10th do,efor
a has been eontinousl and first e purpose Greeley, Colorado,considering
and
ninterru tedl y ' of
amendments to the Weld County
P Y ' o f ed thQ rein Zoning Ordinance as summarized
during a period of at least
below:
fifty-two Consecutive weeks Amend Section 53.4.1 and 53.4.2
prior to by 'hang' Sep[ember 29, 199x"
the first publication of the annexed W "e text. september n, ]ssr'
in the text.
notice; that said newspaperRepeal the Flood Insurance
newspapera is a Study I for Weld revised September
within the meaning of the Emeeergencyr Ma red by the gecy
act of the General Assembly of the Ma remenhe Agency
Adopt b reil�erenee the Flood
State of Colorado, entitled "An Act Insurance by
Study for Weld Count
revised p Se [ember 27, 19r1
to regulate the printing of legal reparea �y the Federal
lood
Emepeal Management Agency.
notices and advertisements, " and Repeal the Weld County Flood
Harsrd tarele Floorict Zoning
amendments thereto; that the notice Rate [haters ivheFRMAssuranel
BuNum Maps (FIbers D80266 RMA 080266
2
0606A, the Ma�B Index 08b266-0001-of which the annexed is a printed 1075,andthe N'Ioodway Map Panel
1.
copy taken from said newspaper, was Number dopt 080266 by 0Wence new Weld
published in said newspaper, and in County Flood Hamm Overlay
District Zoning maps that are the
the regular and entire issue of Flood Insurance rate 0Ba26s(FIRM1 Panel Numbers
Dyer number D, 080298 081 and the Map
Y thereof,
Index 080266 0001 1075. All maps
1,
were revised September 27, 19M,
I to the Federal Emergency
Once a week for MAdopt reterncy.
Adopt b reference a new Weld
successive weeks; that said notice - County Flood mat thane the District Zoning p
080266aYy Map Panel Number was so published in 'said newspaper 080286 0Wl revised September 27,
proper 1991, by the Federal Emergency
P and not in any ' suppl@meat • Management Agency.
thereof , and that the first Al persons m any manner
interested in the proposed
publication of said notice as amendments to the Weld County
Zoning Ordinance are r nested W
aforesaid, was on the Wit and may be hear
Materials pertaining W the
proposed amendments are
. available for public inspection in
all day of () CI-- �� 1 the office of the Clerk to the
a 1t� , Board of County Conmussioners,
located in the Weld Count
Centennial Center, 915 10th Street,
6I third Floor, Greeley, Colorado,,
li and the last on the ^N day of mn through Friday. .i 8:00 a ,,.
O p BOARD OF COUNTY
COMMISSIONERS•
ii(stjsl"..jECWELD COUNTY COLORADO
BY: Donald D.Warden
Weld County Clerk
To The Board
BY: Shelly Miller Deputy
P
DATED: October 21, I I
f vlt PUBLISIIED: Uctobar 24, 1991,
in T The New News
Subscribed and sworn to before
me this d 7'day of er n-t1,z,,..Q-tom ,
191.•
LYF t.W-- Z 4,-..A.,...„ '
,\s„rr,TTICClnn g%Djrnp M Anrnt^117.1C192
(5120 (-"1 V
BEFORE THE WELD COUNTY, COLORADO, PLANNING COMMISSION
RESOLUTION OF RECOMMENDATION TO THE BOARD OF COUNTY COMMISSIONERS
Moved by Don Feldhaus that the following Resolution be introduced for passage by
the Weld County Planning Commission. Be it resolved by the Weld County Planning
Commission the proposed amendments to Section 53 of the Weld County Zoning
Ordinance, repeal and adoption of revised Flood Insurance Rate Maps, Floodway
Maps, and Flood Insurance Study for Weld County be approved for the following
reasons:
1. The existing Zoning Ordinance and maps are in need of revision. These
changes are required for Weld County' s continued participation in the
Federal Flood Insurance program.
2. The proposed amendments will be consistent with the future goals and needs
of the County as set out in the Weld County Comprehensive Plan.
3. The proposed amendments will be consistent with the overall intent of the
Weld County Zoning Ordinance.
Motion seconded by Judy Yamaguchi.
Vote:
For Passage Against Passage
Jean Hoffman
Bill O-Hare
Judy Yamaguchi
LeAnn Reid
Don Feldhaus
Shirley Camenisch
The Vice-Chairman declared the resolution passed and ordered that the proposed
amendments be forwarded to the Board of County Commissioners for further
proceedings.
CERTIFICATION OF COPY
I, Sharyn Ruff, Recording Secretary of the Weld County Planning Commission, do
hereby certify that the above and foregoing Resolution is a true copy of the
Resolution of the Planning Commission of Weld County, Colorado, adopted on
October 15, 1991.
Dated the 15th of October, 1991.
1 I
'Sharyn Ruff
Secretary
()PUS V
MEMORAf1DUf u
Weld County Planning Commission October 1, 1991
To—_ Dam
COLORADO From Department
Department of Planning Services C'
Proposed amendments to Section 53 of the Wel ounty Zoning
saniec :
Ordinance, repeal and adoption of revised Flood Insurance
Rate Maps, Floodway Maps, and flood Insurance Study for wela --
County.
The Department of Planning Services recommends that the proposed amendments be
approved for the following reasons:
1. The existing Zoning Ordinance and maps are in need of revision. These
changes are required for Weld County' s continued participation in the
Federal Flood Insurance program.
2. The proposed amendments will be consistent with the future goals and needs
of the County as set out in the Weld County Comprehensive Plan.
3. The proposed amendments will be consistent with the overall intent of the
Weld County Zoning Ordinance.
CC�A?DS ►'
PROPOSED ZONING ORDINANCE AMENDMENTS
Amend Section 53.4.1 and 53.4.2 by changing "September 28, 1990" to "Revised
September 27, 1991" in the text.
Repeal the Flood Insurance Study for Weld revised September 28, 1990, prepared
by the Federal Emergency Management Agency.
Adopt by reference the Flood Insurance Study for Weld County, revised September
27, 1991, prepared by the Federal Emergency Management Agency.
Repeal the Weld County Flood Hazard Overlay District Zoning Maps that are the
Flood Insurance Rate Maps (FIRM) Panel Numbers 080266 0605A, 080266 0608A, the
Map Index 080266-0001-1075, and the Floodway Map Panel Number 080266 0001.
Adopt by reference new Weld County Flood Hazard Overlay District Zoning maps that
are the Flood Insurance Rate Maps (FIRM) Panel Numbers 080266 0605D, 080266
0608D, and the Map Index 080266 0001 1075. All maps were revised September 27,
1991, by the Federal Emergency Management Agency.
Adopt by reference a new Weld County Flood Hazard Overlay District Zoning map
that is the Floodway Map Panel Number 080266-0001 revised September 27, 1991, by
the Federal Emergency Management Agency.
-,
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FLOO 1 , , ,
ALAI_ , nrIPPI. _
INS / A NCEt1 ` r Itt
STUD S A
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WELD COUNT
COLORADO
UNINCORPORA D AREAS
AND
TOWN OF E i • N,
COLORADO
WELD COUNTY
REVISED:SEPTEMBER 27 :91
NAY m44,
' a Feder Emergency Manat ent Agency
any o �� COMMUNITY NUMBER - 080
NOTICE TO
FLOOD INSURANCE STUDY USERS
Communities participating in the National Flood Insurance Program have
established repositories of flood hazard data for floodplain management
and flood insurance purposes. This Flood Insurance Study may not
contain all data available within the repository. It is advisable to
contact the community repository for any additional data.
This publication incorporates revisions to the original Flood Insurance
Study. These revisions are presented in Section 9.0.
TABLE OF CONTENTS
Page
1.0 INTRODUCTION 1
1.1 Purpose of Study 1
1.2 Coordination 1
1.3 Authority and Acknowledgments 2
2.0 AREA STUDIED 2
2.1 Scope of Study 2
2.2 Community Description 4
2.3 Principal Flood Problems 6
2.4 Flood Protection Measures 9
3.0 ENGINEERING METHODS 9
3.1 Hydrologic Analyses 9
3.2 Hydraulic Analyses 11
4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 15
4.1 Floodplain Boundaries 15
4.2 Floodways 16
5.0 INSURANCE APPLICATION 17
5.1 Reach Determinations 18
5.2 Flood Hazard Factors 18
5.3 Flood Insurance Zones . 33
5.4 Flood Insurance Rate Map Description 34
6.0 OTHER STUDIES 34
7.0 LOCATION OF DATA 40
8.0 BIBLIOGRAPHY AND REFERENCES 40
9.0 REVISIONS DESCRIPTION 44
9.1 First Revision 44
i
TABLE OF CONTENTS (Cont'd)
FIGURES
Page
Figure 1 - Vicinity Map 3
Figure 2 - Historic Flooding 7
Figure 3 - Historic Flooding 7
Figure 4 - Historic Flooding 8
Figure 5 - Floodway Schematic . . 18
TABLES
Table 1 - Summary of Discharges 12
Table 2 - Floodway Data 19
Table 3 - Flood Insurance Zone Data 35
EXHIBITS
Exhibit 1 — Flood Profiles
South Platte River Panels 01P-10P
U.S. Highway 34 Levee Overflow Channel . . . . Panels 11P-12P
Cache La Poudre River Panels 13P-18P
Sheep Draw Panels 19P-24P
Ashcroft Draw Panels 25P-31P
Eaton Draw Panels 32P-35P
Tri-Area Drainageway Panels 36P-41P
Tri-Area Drainageway Overflow Channel Panel 42P
Big Thompson River Panels 43P-53P
Coal Creek Panels 54P-55P
Cache La Poudre River at Windsor Panels 56P-63P
Kodak Waste Water Treatment
Plant Divided Flow Panels 64P-65P
Windsor Waste Water Treatment
Plant Divided Flow Panel 66P
State Highway 257 Divided Flow Panel 67P
State Highway 392 Divided Flow Panels 68P-69P
Exhibit 2 - Flood Boundary and Floodway Map
PUBLISHED SEPARATELY
Flood Insurance Rate Map Index
Flood Insurance Rate Map
ii
FLOOD INSURANCE STUDY
TOWN OF EATON AND WELD COUNTY, COLORADO
1.0 INTRODUCTION
1.1 Purpose of Study
This Flood Insurance Study revises and updates a previous Flood
Insurance Study/Flood Insurance Rate Map for the unincorporated
areas of Weld County and the incorporated areas of the Town of
Eaton, Weld County, Colorado. This information will be used by
Weld County and the Town of Eaton to update existing floodplain
regulations as part of the Regular Phase of the National Flood
Insurance Program (NFIP). The information will also be used by
local and regional planners to further promote sound land use and
floodplain development.
In some states or communities, floodplain management criteria or
regulations may exist that are more restrictive or comprehensive
than the minimum Federal requirements. In such cases, the more
restrictive criteria take precedence and the State (or other
jurisdictional agency) will be able to explain them.
1.2 Coordination
The identification of initial areas requiring detailed study was
done at a meeting attended by personnel from the study contractor,
Federal Emergency Management Agency (FEMA), and the Weld County
Planning Department on April 22, 1976.
The U.S. Army Corps of Engineers (COE), Omaha District, provided
floodplain data on the Cache La Poudre River and the South Platte
River for use in preparing this Flood Insurance Study.
The results of the original study were reviewed at final
coordination meetings held on December 20, 1978, for Weld County
and on January 8, 1979, for the Town of Eaton. Attending the
meetings were representatives of FEMA, the study contractor, Weld
County, and the Town of Eaton. No problems were raised at these
meetings.
Further flood hazards exist along Coal Creek south of the Union
Pacific Railroad within the Town of Erie and Weld County. On
October 6, 1987, a meeting was held between representatives of
FEMA, the Town of Erie, and the U.S. Department of the Interior,
Bureau of Reclamation to discuss the detailed analysis of these
flood hazards. The town provided maps, which were used in the
analysis.
In addition, the U.S. Soil Conservation Service (SCS) , U.S.
Geological Survey (USGS), COE, and Colorado Water Conservation
Board (CWCB) were contacted for pertinent information regarding
flood hazards within the Town of Erie and Weld County. The SCS
provided a copy of their Flood Hazard Analysis, "Coal Creek and
Rock Creek, Boulder, and Weld Counties, Colorado," dated October
1976. The SCS also provided hydraulic backwater computer model
input data for Coal Creek near Erie. The USGS provided copies of
Flood Prone Area Maps for the study area. The COE indicated that
they had no pertinent technical information that could be included
in the Coal Creek study.
The CWCB provided a copy of the Technical Addendum, "Floodplain
Information, Flood Control and Floodplain Management Plan for Coal
Creek at Erie, Colorado," prepared by Water Resource Consultants,
Inc. (WRC), dated August 1980. The addendum contained copies of
the HEC-2 computer modeling for a portion of the study area.
Robinson Engineering, Inc. (REI), was contacted in response to a
recommendation from the Town of Erie. REI provided detailed
topographic mapping for a portion of this study area.
1.3 Authority and Acknowledgments
The source of authority for this Flood Insurance Study is the
National Flood Insurance Act of 1968, as amended.
The initial hydrologic and hydraulic analyses for the major sources
of flooding were performed by Gingery Associates, Inc. , for FEMA,
under Contract No. H-4017. This work, which was completed in
December 1977, covered all significant flooding sources affecting
Weld County and the Town of Eaton at that time. The hydrologic and
hydraulic analyses for the Big Thompson River were performed by the
COE, Omaha District, in the Flood Plain Information Report dated
February 1978.
The hydrologic and hydraulic analyses for Coal Creek, south of the
Union Pacific Railroad, were performed by the U.S. Department of
the Interior, Bureau of Reclamation for FEMA, under Contract
No. EMW-87-E-2551. This study was completed in August 1988.
2.0 AREA STUDIED
2.1 Scope of Study
This Flood Insurance Study covers the unincorporated areas of Weld
County and the incorporated areas of the Town of Eaton, Weld
County, Colorado. The area of study is shown on the Vicinity Map
(Figure 1).
The incorporated Cities of Evans, Fort Lupton, Greeley, Gilcrest,
and the incorporated Towns of Ault, Dacono, Erie, Firestone,
Frederick, Garden City, Grover, Hudson, Johnstown, Keeneburg,
Keota, Kersey, La Salle, Mead, Milliken, Nunn, Pierce, Platteville,
Raymer, Rosedale, Severance, and Windsor were not included in the
study. The Pawnee National Grasslands was not studied.
2
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FIGURE 1
The following streams were studied by detailed methods: South
Platte River, U.S. Highway 34 Levee Overflow Channel , Cache La
Poudre River, Sheep Draw, Ashcroft Draw, Eaton Draw, Tri-Area
Drainageway, Tri-Area Drainageway Overflow Channel, Coal Creek, and
the Big Thompson River.
Those areas studied by detailed methods, with the exception of Coal
Creek, were chosen with consideration given to all proposed
construction and forecasted development through 1982.
Approximate studies were done on the Cache La Poudre River and the
South Platte River in areas of Sparse development and on Idaho and
Crow Creeks.
2.2 Community Description
Weld County is located in northeastern Colorado and is bounded by
Wyoming to the north, Logan and Morgan Counties to the east, Adams
County to the south, and Boulder and Larimer Counties to the west.
Gently rolling hills form the terrain in Weld County, and primary
land use is for irrigated crops and cattle grazing. The major
industries in the county are cattle feedlots, meat processing
plants, and sugar beet processing plants.
The population of Weld County was 123,438 according to the 1980
census (Reference 1). The climate in Weld County is typical of the
eastern plains of Colorado. The average annual precipitation
throughout the county is approximately 12.3 inches, and the mean
annual temperature is approximately 480 F (Reference 2).
The South Platte River detailed study reach is approximately 8.7
miles long. The river flows northeast in a relatively well-defined
channel from 300 to 600 feet wide and from 6 to 8 feet deep. The
channel, typically braided, is situated in a broad, shallow
floodplain ranging in width from 3,000 to 5,000 feet. Its sandy
streambed slopes at approximately 7 feet per mile throughout the
study reach. Coverage on the floodplain includes cottonwood trees
near the banks and row crops and pastureland elsewhere.
Residential development is sparse outside of the incorporated
areas. The primary underlying soil types are of the Fluvaquents-
Fluvents association, which are deep and poorly drained
(Reference 3).
The U.S. Highway 34 Levee Overflow Channel parallels the South
Platte River and U.S. Highway 34, extending approximately 0.87
mile. Flooding in this area is controlled by the South Platte
River.
The Cache La Poudre River study reach is approximately 14.8 miles
long with a channel gradient of 7.3 feet per mile. The river flows
in a southeasterly direction through the county. The development
within the floodplain consists of agriculture-related building
outside of the incorporated areas. The soil types within the Cache
4
La Poudre River floodplain are also of the Fluvaquents-Fluvents
association (Reference 3).
Sheep Draw flows in a northeasterly direction to its confluence
with the Cache La Poudre River. The length of the study reach is
approximately 5.2 miles. Topography in the basin consists of
gently rolling hills, with basin slopes varying from 1 to 3
percent. The primary land use in the basin is for irrigated
croplands and pastures. The major soil types in the basin are of
the Ascalon-Olney-Vona, Weld-Andena-Colby, and Fluvaquents-Fluvents
associations (Reference 3).
The Ashcroft Draw study reach, approximately 3.2 miles long, flows
southeast to its confluence with the South Platte River,
approximately 3 miles southwest of the City of Greeley. Basin
slopes range from approximately 3 percent in the lower reaches to
over 8 percent near the headwaters. Most of the basin is utilized
as irrigated cropland, with a small portion devoted to rangeland
and urbanized areas. The major soil types in the Ashcroft Draw
basin are of the Ascalon-Olney-Vona association (Reference 3).
The Eaton Draw study is comprised of two areas, one near the
confluence of the Cache La Poudre River (1.61 miles long) and one
near the Town of Eaton (2.08 miles long). In February 1978, the
Town of Eaton annexed a part of Weld County along Eaton Draw
containing floodplains. Eaton Draw flows south in a long, narrow
basin between the Town of Nunn and the City of Greeley. The basin
width varies from 1 to 3 miles, and the basin slopes vary from 2 to
5 percent. Most of the basin is used as irrigated cropland and
pasture. Natural grasses and sage brush form most of the ground
cover. The major soil types in the basin are of the Nunn-Dacono-
Altvan, Ascalon-Platner-Stoneham, Renohill-Shingle, Weld-Adena-
Colby, and Kim-Otero associations (Reference 3).
The Tri-Area Drainageway (Frederick-Firestone-Dacono drainage
basin) flows north through the Town of Dacano, Frederick, and
Firestone to its confluence with the St. Vrain River. The portions
of the drainageway outside of the towns' corporate limits are
included in the study. Basin slopes range from 1 to 2 percent and
channel slopes vary from 0.4 to 1.0 percent. Land use in the basin
is approximately 90 percent agricultural and 10 percent urban. The
spoil types are of the Weld-Adena-Colby, Platner-Ulm-Renohill, and
Ascalon-Olney-Vona associations (Reference 3).
The Big Thompson River study reach is approximately 12.4 miles
long. The river flows in a general easterly direction to its
confluence with the South Platte River about 5 miles southwest of
Greeley. The 100-year floodplain width varies from a minimum near
350 feet to a maximum near 3,500 feet with an average of 1,750
feet. The streambed has an average slope of 8 feet per mile
through the study reach. The channel is alluvial and meanders
through a u-shaped valley. The major portion of the floodplain in
the study reach is in agricultural use. Few buildings of any type
5
exist on this floodplain. Those that do exist are primarily
agriculturally oriented.
2.3 Principal Flood Problems
Flooding along the South Platte River normally occurs between May
and August, with the most frequent flooding occurring in June.
Floods can result from intense local rainfall, as in 1965, or
general rainstorms lasting several days, as in 1969 and 1973. Both
types of flooding may be augmented by snowmelts. Floods on the
South Platte River have occurred as follows: May 1876; late May
and early June 1914; June 1921; from August 30 to September 4,
1938; April and May 1942; May and June 1949; May 1951; June 1965;
May 1969; and, May 1973. The floods of June 1921 and May 1973 are
estimated to have frequencies of approximately 100 years.
Damaging floods occurred in the study area of the Cache La Poudre
River in 1876, 1884, 1904, 1917, 1923, 1947, 1949, 1951, 1964, and
1965. The largest flood in recorded history was in 1917 with an
estimated discharge of 13,000 cubic feet per second (cfs) in the
are of the City of Greeley (Reference 4).
Historic records of flooding on Eaton Draw are not very concise. A
major flood is known to have occurred on May 1, 1977, when flood
depths in the vicinity of the Town of Eaton approximated those of
the 100-year flood. Other floods occurred on various parts of
Eaton Draw in 1935, 1951, 1954, 1961, 1965, 1972, and 1974.
The most significant floods of recent times along the Tri-Area
Drainageway occurred in 1957, 1961, and 1975. On June 3, 1961, 2
to 4 inches of rain fell in a 2-hour period in the drainage basin.
The Tri-Area Drainageway flows swelled, flooding sections of the
Towns of Firestone, Frederick, and Dacono. This was similar to the
flood of 1957, which caused structural damage to the same area. In
1965, heavy rains and hail caused extensive flooding, and housing
damages were reported in the thousands of dollars.
Local residents reported shallow flooding in the U.S. Highway 34
Levee Overflow Channel during May 1973, with no resulting damage.
No flood history is available for Sheep Draw or Ashcroft Draw, as
these areas have not been extensively developed.
Photographs of the 1977 flood on Eaton Draw and the 1969 flood on
the South Platte River are provided in Figures 2 through 4.
Flooding along the Big Thompson River generally occurs between May
and July. However, annual peak discharges have been experienced
from March through September. Floods can have considerably
different characteristics depending upon the location within the
basin and generally have a duration of about 1 day. In July 1976,
heavy rainfall , amounting to as much as 12 inches in 4 hours, fell
on the evening of July 31 in the upper Big Thompson River basin, in
6
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Figure 2. Flooding on South Platte River Near the City of Evans (1969)
1 ,
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Figure 3. Flooding on Eaton Draw Along Weld County Road 76 Near the Town of
Eaton (May 1, 1977)
7
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Figure 4. Flooding on Eaton Draw Along Weld County Road 74 (May 1, 1977)
(Town of Eaton Sewage Treatment Plant in Right of Photo)
8
the general vicinity of Estes Park, Glen Haven, and Drake. The
estimated peak discharge at the USGS stream gaging station located
6 miles east of Drake was 31,200 cfs, about 4 times larger than the
previous recorded peak discharge. Floods on the Big Thompson River
have occurred as follows: June 1921; June 1923; September 1938;
June 1949; and, August 1951.
2.4 Flood Protection Measures
The sole flood-control structure that will reduce discharges on the
stream reaches studied in this report is Ashcroft Draw. At this
location the Arrowhead Reservoir reduces the 100-year discharge
from 1,546 cfs to 654 cfs. Levees along the South Platte River
help control flooding in some locations, but areas protected from
the 100-year flood are not very widespread.
3.0 ENGINEERING METHODS
For the flooding sources studied in detail in the community, standard
hydrologic and hydraulic study methods were used to determine the flood
hazard data required for this study. Flood events of a magnitude which
are expected to be equaled or exceeded once on the average during any
10-, 50-, 100-, or 500-year period (recurrence interval), have been
selected as having special significance for floodplain management and
for flood insurance premium rates. These events, commonly termed the
10-, 50-, 100-, and 500-year floods, have a 10, 2, 1, and 0.2 percent
chance, respectively, of being equaled or exceeded during any year.
Although the recurrence interval represents the long-term average period
between floods of a specific magnitude, rare floods could occur at short
intervals or even within the same year. The risk of experiencing a rare
flood increases when periods greater than 1 year are considered. For
example, the risk of having a flood which equals or exceeds the 100-year
flood (1-percent chance of annual exceedence) in any 50-year period is
approximately 40 percent (4 in 10), and for any 90-year period, the risk
increases to approximately 60 percent (6 in 10). The analyses reported
herein reflect flooding potentials based on conditions existing in the
county at the time of completion of this study. Maps and flood eleva-
tions will be amended periodically to reflect future changes.
3.1 Hydrologic Analyses
Hydrologic analyses were carried out to establish the peak
discharge-frequency relationships for floods of the selected
recurrence intervals for each stream studied in detail in the
county.
The COE provided the 10-, 50-, 100-, and 500-year flood discharges
for the South Platte River (Reference 5), and the 10-, 50-, and
100-year discharges for the Cache La Poudre River (Reference 4).
The 500-year discharge for the Cache La Poudre River was obtained
from a straight line extrapolation of these values on log-
probability paper. The COE studied the discharge-drainage area
relationship for the Cache La Poudre River taking into
9
consideration channel storage along the study reach. As a result,
some peak discharge values for portions of the river show an
increasing velocity with a decreasing drainage area.
Peak discharges for the 10- and 100-year floods on Sheep Draw were
computed using the SCS Technical Release No. 20 computer program
(Reference 6). Basin characteristics needed for the program were
taken from the USCS topographic maps, at a scale of 1:24,000, with
a contour interval of 10 feet (Reference 7) . Precipitation
distributions were developed from information provided in the
National Oceanic and Atmospheric Administration Atlas
(Reference 8). The 50- and 500-year discharges were obtained by
straight line interpolation and extrapolation of the 10- and 100-
year values plotted on log-probability paper.
Discharge hydrographs for the 10- and 100-year floods on Ashcroft
and Eaton Draws were developed using methods suggested in Chapter
16 of the National Engineering Handbook, published by the SCS
(Reference 9). Drainage areas and stream lengths necessary to
construct the hydrographs were taken from USGS topographic maps at
a scale of 1:24,000, with a contour interval of 10 feet (References
10 and 11). Precipitation distributions were developed from
information provided in the National Oceanic and Atmospheric
Administration Atlas (Reference 8). The hydrographs for Ashcroft
Draw were routed through Arrowhead Reservoir using the Storage-
Indication Method outline in Chapter 17 of the National Engineering
Handbook (Reference 9). The 50- and 500-year discharges were
obtained by straight line interpolation and extrapolation of the
10- and 100-year values plotted on log-probability paper.
Discharges for the Tri-Area Drainageway were computed using the SCS
Technical Release No. 20 (Reference 6). Rainfall data used in the
hydrologic analyses were obtained from the National Oceanic and
Atmospheric Administration Atlas for Colorado (Reference 8), and
soil and land use information were taken from maps prepared by the
SCS (Reference 3).
Discharge magnitudes for floods on the Big Thompson River were
based upon an analysis of stream gaging data at the USGS stream
gages located near Drake and La Salle. Because there are no
streamflow gaging records between the La Salle gage and the
upstream limit of study, discharge-probability relationships were
developed for the intervening drainage area using unit hydrographs
and flood routing techniques and rainfall probabilities from U.S.
Weather Bureau Technical Publication No. 40.
The peak discharges for the 10-, 50-, 100-, and 500-year floods for
Coal Creek were developed by the SCS in a report entitled Flood
Hazard Analyses, Coal Creek and Rock Creek, Boulder and Weld
Counties, Colorado (Reference 12) . The SCS used synthetic
rainfall-runoff procedures, as described in the SCS' s National
Engineering Handbook (Reference 13), and the TR-20 computer program
for flood routing (Reference 14) in order to establish the selected
discharges along the stream.
10
Peak discharge-drainage ar,ta relationships tor South Platte River,
Cache La Poudre River, Sheep, Ashcroft, and Eaton Draws, Tri-Area
Drainageway, Coal Creek, and the Big Thompson River are shown in
Summary of Discharges (Table 1).
Discharges for U.S. Highway 34 Levee Overflow Channel were obtained
using a weir flow equation,
Q = CLH3/2
where Q = Total flow over the weir
C = Coefficient of discharge
L = Effective length of weir controlling flow
H = Difference between the energy grade line elevation and
the roadway crest elevation
Values of H were determined by using the COE HEC-2 computer program
(Reference 15) where the flow was confined to the channel. The
100- and 500-year discharges ranged from 550 to 600 cfs and from
7,000 to 12,500 cfs, respectively.
The 10-, 50-, 100-, and 500-year discharges for the Tri-Area
Drainageway Overflow Channel are 240, 780, 850, and 1,100 cfs,
respectively.
3.2 Hydraulic Analyses
Analyses of the hydraulic characteristics of streams in the county
were carried out to provide estimates of the elevations of floods
of the selected recurrence intervals along each stream studied in
the county.
Cross section data for the South Platte River were obtained from
field surveys done by the COE for the Special Flood Hazard
Information Report (Reference 5) and by field surveys performed by
the study contractor. All bridges were surveyed by the COE to
obtain elevation data and structural geometry. Roughness
coefficients (Manning' s "n") were estimated by field inspection.
Channel "n" values ranged from 0.035 to 0.100. Water-surface
profiles were computed using the COE HEC-2 computer program
(Reference 12). Starting water-surface elevations for the South
Platte River were determined using the slope area method 2,000 feet
downstream of the study reach.
Cross sections for the Cache La Poudre River were taken from
topographic maps by COE for their Flood Plain Information Report
(Reference 4). All bridges were field surveyed to obtain elevation
data and structural geometry. Roughness coefficients were selected
by the COE. The channel "n" value was 0.040, and the overbank "n"
values ranged from 0.060 to 0.100. The 100-year water-surface
profile was computed by the COE (Reference 15). Profiles for the
10-, 50-, and 500-year floods were hand calculated using the step-
11
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13
backwater method and stage discharge curves at several cross
sections on the Cache La Poudre River. Starting water-surface
elevations were taken from those determined for the South Platte
River.
Cross section data for Sheep, Ashcroft, and Eaton Draws, and the
Tri-Area Drainageway were obtained from field surveys by the study
contractor. Additional cross section data for a part of the Tri-
Area Drainageway were obtained from 1-foot contour interval ,
1:1,200 scale topographic mapping produced as a part of a 1975
drainageway study for Weld County (Reference 16). Additional cross
section data for a portion of the overbank area of Sheep Draw were
obtained from 2-foot contour interval , 1 : 2 ,400 , scale
photogrammetric maps (Reference 17). All bridges were field
surveyed to obtain elevation data and structural geometry.
Roughness coefficients were estimated from field inspection.
Channel "n" values for Sheep, Ashcroft, and Eaton Draws and the
Tri-Area Drainageway, including the Tri-Area Drainageway Overflow
Channel, ranged from 0.030 to 0.040, from 0.035 to 0.040, from
0.016 to 0.050, and from 0.045 to 0.060, respectively, and overbank
"n" values ranged from 0.040 to 0.070, from 0.040 to 0.060, from
0.040 to 0.070, and from 0.045 to 0.090, respectively. The COE
HEC-2 computer program was used to compute water-surface profiles
for all four streams (Reference 15). Starting elevations were
determined from slope-area computations at the downstream sections.
Cross section data for Coal Creek were obtained from topographic
maps at a scale of 1:4,800, with contour intervals of 2 and 4 feet
(Reference 18). Field measurements were taken by the SCS to obtain
elevation data and structural geometry of all bridges and culverts.
Roughness coefficients for Coal Creek south of the Union Pacific
Railroad were determined by the WRC (Reference 19). These values
were reviewed and approved by the CWCB. The "n" values range from
0.075 in the channel to 0.055 in the overbank.
Topographic mapping for the Big Thompson River was established by
photogrammetric methods from flights made in June 1975. Bridge and
roadway survey data were provided by the CWCB.
Water-surface profiles were developed using the COE HEC-2 computer
program (Reference 15). The computations were based on channel and
floodplain conditions as represented by survey data gathered in
June 1975 and as supplemented by later field investigations
(Reference 20).
Locations of selected cross sections used in the hydraulic analyses
are shown on the Flood Profiles. For stream segments for which a
floodway is computed (Section 4.2), selected cross section
locations are also shown on the Flood Boundary and Floodway Map.
Flood profiles were drawn showing computed water-surface elevations
to an accuracy of 0.5 foot for floods of the selected recurrence
intervals.
14
The approximate flooding on Crow Creek was determined from normal-
depth calculations and weir calculations at a county road. The
approximate flooding on Idaho Creek was based upon engineering
judgment and field inspection.
All elevations are referenced to the National Geodetic Vertical
Datum (NGVD) of 1929. Elevation reference marks used in this study
and the descriptions of those marks, are shown on the maps.
4.0 FLOODPLAIN MANAGEMENT APPLICATION
The National Flood Insurance Program (NFIP) encourages State and local
governments to adopt sound floodplain management programs. Therefore,
each Flood Insurance Study provides 100-year flood elevations and
delineations of the 100- and 500-year floodplain boundaries and 100-year
floodway to assist communities in developing floodplain management
measures.
4.1 Floodplain Boundaries
In order to provide a national standard without regional
discrimination, the 100-year flood has been adopted by FEMA as the
base flood for floodplain management purposes. The 500-year flood
is employed to indicate additional areas of flood risk in the
community. For each stream studied in detail, the boundaries of
the 100- and 500-year floods have been delineated using the flood
elevations determined at each cross section; between cross
sections, the boundaries were interpolated using topographic and
photogrammetric maps at the scale and contour interval as follows
for each stream:
South Platte River (detailed study from City of Evans to
confluence with Cache La Poudre River) , scale 1:24,000,
enlarged to a scale of 1:7,200, with a contour interval of 10
feet (Reference 21)
Cache La Poudre River, scale 1: 12,000 enlarged to a scale of
1:7,200, with a contour interval of 4 feet (References 4 and
22)
Sheep Draw, scale 1:2,400, with a contour interval of 2 feet
(Reference 17)
Ashcroft Draw, scale 1:24,000, enlarged to a scale of 1:7,200,
with a contour interval of 10 feet (References 7 and 10)
Eaton Draw, scale 1:24,000, enlarged to a scale of 1:7,200,
with a contour interval of 10 feet (Reference 11)
Tri-Area Drainageway, scale 1:24,000, enlarged to a scale of
1:7,200, with a contour interval of 1 foot (Reference 16)
15
Big Thompson River, scale 1 :2,400, reduced to 1:6,000 with a
contour interval of 2 feet (Reference 17)
Coal Creek, scale 1:4,800, with a contour interval of 2 and 4
feet (Reference 19)
In cases where the 100- and 500-year flood boundaries are close
together, only the 100-year flood boundary has been shown.
The approximate flood boundaries for the South Platte River and the
Cache La Poudre River were taken from the 100-year flood boundaries
developed by the COE (References 4, 5, and 21).
Approximate flood boundaries on streams in the study area were
delineated using topographic maps at a scale and contour interval
as follows for each stream:
South Platte River (from Adams County boundary to the City of
Evans and downstream of the Cache La Poudre River to Morgan
County), scale 1:24,000, enlarged to a scale of 1:12,000, with
a contour interval of 10 feet (References 10 and 23)
Cache La Poudre River, scale 1:12,000 enlarged to a scale of
1:7,200, with a contour interval of 4 feet (Reference 4 and
21)
Crow Creek, scale 1:24,000, with a contour interval of 10 feet
(Reference 24)
Idaho Creek, scale 1:24,000, enlarged to a scale of 1:2,400,
with a contour interval of 2 feet (Reference 25)
Approximate flood boundaries in some portions of the study area
were taken from FEMA' s Flood Hazard Boundary Map (Reference 20).
Flood boundaries for the 100- and 500-year floods are shown on the
Flood Boundary and Floodway Map.
Small areas within the flood boundaries may lie above the flood
elevations, and therefore, not be subject to flooding; because of
limitations of the map scale, such areas are not shown.
4.2 Floodways
Encroachment on floodplains, such as structures and fill, reduces
flood-carrying capacity, increases flood heights and velocities,
and increases flood hazards in areas beyond the encroachment
itself. One aspect of floodplain management involves balancing the
economic gain from floodplain development against the resulting
increase in flood hazard. For purposes of the NFIP, a floodway is
used as a tool to assist local communities in this aspect of
floodplain management. Under this concept, the area of the 100-
year flood is divided into a floodway and a floodway fringe. The
floodway is the channel of a stream, plus any adjacent floodplain
16
areas, that must be kept free of encroachment so that the 100-year
flood can be carried without substantial increases in flood
heights. Minimum Federal standards limit such increases in flood
heights to 1.0 foot, provided that hazardous velocities are not
produced.
The floodways for all streams studied by detailed methods were
computed on the basis of equal conveyance reduction from each side
of the floodplain. The results of these computations are tabulated
at selected cross sections for each stream segment for which a
floodway is computed (Table 2).
A floodway is not shown for U.S. Highway 34 Levee Overflow Channel
because flooding in this area is controlled by the South Platte
River.
No floodway was computed for the detailed study reach of the Big
Thompson River.
As shown on the Flood Boundary and Floodway Map, the floodway
boundaries were determined at cross sections ; between cross
sections, the boundaries were interpolated. In cases where the
floodway and 100-year flood boundaries are close together, only the
floodway boundary has been shown.
The area between the floodway and the boundary of the 100-year
flood is termed the floodway fringe. The floodway fringe thus
encompasses the portion of the floodplain that could be completely
obstructed without increasing the water-surface elevation of the
100-year flood more than 1 .0 foot at any point. Typical
relationships between the floodway and the floodway fringe and
their significance to floodplain development are shown in Figure 5.
5.0 INSURANCE APPLICATION
In order to establish actuarial insurance rates, the FEMA has developed
a process to transform the data from the engineering study into flood
insurance criteria. This process includes the determination of reaches,
Flood Hazard Factors (FHFs), and flood insurance zone designations for
each flooding source studied in detail affecting the unincorporated
areas of Weld County.
17
100-YEAR FLOODPLAIN
F- FLOODWAY i - E FLOODWAY - - FLOODWAY _
FRINGE FRINGE
F STREAM y
CHANNEL
FLOOD ELEVATION WHEN
CONFINED WITHIN FLOODWAY
ENCROACHMENT ENCROACHMENT
\ C D
• •_ _____-----1\_
E" -= SURCHARGE' I r
A .w..w SP..w R
,t, I \
AREA OF FLOODPLAIN THAT COULD BE USE` /OD ELEVATION BEFORE
FOR DEVELOPMENT BY RAISING GROUND ENCROACHMENT ON FLOODPLAIN
LINE AB IS THE FLOOD ELEVATION BEFORE ENCROACHMENT.
LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT.
'SURCHARGE IS NOT TO EXCEED 1.0 FOOT(FIA REQUIREMENT)OR LESSER AMOUNT IF SPECIFIED BY STATE.
Figure 5. Floodway Schematic
5.1 Reach Determinations
Reaches are defined as lengths of watercourses having relatively
the same flood hazard, based on the average weighted difference in
water-surface elevations between the 10- and 100-year floods. This
difference does not have a variation greater than that indicated in
the following table for more than 20 percent of the reach:
Average Difference Between
10- and 100-Year Floods Variation
Less than 2 feet 0.5 foot
2 to 7 feet 1.0 foot
7.1 to 12 feet 2.0 feet
More than 12 feet 3.0 feet
The locations of reaches determined for the flooding sources of the
unincorporated areas of Weld County are shown on the Flood Profiles
and summarized in Table 3. The reach of Eaton Draw affecting the
Town of Eaton is shown on Profile 34P.
5.2 Flood Hazard Factors
The FHF is the FEMA device used to correlate flood information with
insurance rate tables. Correlations between property damage from
18
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floods and their FHF are used to set actuarial insurance premium
rate tables based on FHFs from 005 to 200.
The FHF for a reach is the average weighted difference between the
10- and 100-year flood water-surface elevations expressed to the
nearest 1/2 foot, and shown as a three-digit code. For example, if
the difference between water-surface elevations of the 10- and 100-
year floods in 0.7 foot, the FHF is 005; if the difference is 1.4
feet, the FHF is 015; if the difference is 5.0 feet, the FHF is
050. When the difference between the 10- and 100-year water-
surface elevations is greater than 10.0 feet, accuracy for the FHF
is rounded to the nearest foot.
5.3 Flood Insurance Zones
After the determination of reaches and their respective FHFs, the
entire unincorporated area of Weld County was divided into zones,
each having a specific flood potential or hazard. Each zone was
assigned one of the following flood insurance zone designations:
Zone A: Special Flood Hazard Areas inundated by
the 100-year flood , determined by
approximate methods ; no base flood
elevations shown or FHFs determined.
Zone AO: Special Flood Hazard Areas inundated by
types of 100-year shallow flooding where
depths are between 1.0 and 3.0 feet;
depths are shown, but no FHFs are
determined.
Zones Al through A9: Special Flood Hazard Areas inundated by
the 100-year flood, determined by detailed
methods; base flood elevations shown, and
zones subdivided according to FHFs.
Zone B: Areas between the Special Flood Hazard
Areas and the limits of the 500-year
flood, including areas of the 500-year
floodplain that are protected from the
100-year flood by dike, levee, or other
water control structure; also areas
subject to certain types of 100-year
shallow flooding where depths are less
than 1.0 foot; and areas subject to 100-
year flooding from sources with drainage
areas less than 1 square mile. Zone B is
not subdivided.
Zone C: Areas of minimal flooding.
Zone D: Areas of undetermined, but possible flood
hazard.
33
The flood elevation differences, FHFs, flood insurance zones, and
base flood elevations for each flooding source studied in detail in
the county are summarized in Table 3.
5.4 Flood Insurance Rate Map Description
The Flood Insurance Rate Map for the unincorporated areas of Weld
County is, for insurance purposes, the principal result of the
Flood Insurance Study. This map (published separately) contains
the official delineation of flood insurance zones and base flood
elevation lines. Base flood elevation lines show the locations of
the expected whole-foot water-surface elevations of the base (100-
year) flood. This map is developed in accordance with the latest
flood insurance map preparation guidelines published by FEMA.
6.0 OTHER STUDIES
The COE published the Special Flood Hazard Information Report, South
Platte River, Volume I, April 1977 (Reference 5), which is a study of
the South Platte River in Weld County, to compare the 1973 flood with
the 100-year flood. The information provided varies from stage-
discharge relationships at each cross section in the rural areas to
water-surface profiles in the urban areas. The profiles in this report
differ from the COE profiles by more than 0.5 foot in a few places. At
cross section E, the COE did not consider the skew of the bridge, which
causes increased effective pier widths and higher elevations.
Additional cross sections taken below Cross Section I for this report
indicated that the 100-year flood would be confined by levees, thus
raising the water surface above that computed by the COE. At U.S.
Highway 85, the COE considered the Latham Ditch as carrying part of the
100-year flow. As this is not considered by FEMA policy, the elevations
in this report are higher than the COE computed elevations.
The COE completed a Flood Plain Information report on the Cache La
Poudre River at the City of Greeley in March 1974 (Reference 4). The
discharges and 100-year water-surface elevations used in this Flood
Insurance Study were taken from the COE report. Elevations shown in
this study differ from those presented in the Flood Plain Information
Report due to the use of different cross section stationing.
A drainage study has been completed for the Tri-Area Drainageway at the
Town of Firestone which includes flood discharges and proposed
improvements (Reference 16). These discharges, developed by using the
Colorado Urban Hydrograph Procedure (CUHP), are approximately 25 percent
higher than those computed for this study. Because of the difficulty in
using the CUHP in undeveloped, agricultural watersheds, the discharges
determined in this report are considered appropriate. The discharges
reported here also include the effect of failure of the Frederick Levee,
which was not considered in the drainage study.
Gingery Associates, Inc. , has completed or is in the process of
completing Flood Insurance Studies for the Cities of Greeley, Evans, and
Fort Lupton, and the Towns of Frederick, Firestone, Dacono, Erie,
34
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Milliken, Windsor, Nunn, and Pierce, all in Weld County (References 27
through 37, respectively). These reports were well coordinated and,
therefore, will be in complete agreement.
The Omaha District of the COE is preparing a study of Sheep Draw.
Contact was made with the COE and comparison of the hydrologic data
revealed that both studies are in agreement.
A report, concerning the potential flood hazards of Coal Creek in the
area around the Town of Erie entitled Flood Hazard Analyses, Coal Creek
and Rock Creek, was prepared by the SCS in October 1976 (Reference 1).
That report was modified in August 1980, by WRC, in their report
entitled Floodplain Information, Flood Control , and Floodplain
Management. This Flood Insurance Study is integrated with that study,
north of Briggs Street; however, new HEC-2 runs south of Briggs Street
were developed for the Coal Creek West Line Overflow and Coal Creek and
supersede that portion of the above-mentioned WRC study.
This report supersedes the previous Flood Insurance Study (Reference 38)
and should be considered authoritative for purposes of the NFIP.
7.0 LOCATION OF DATA
Survey, hydrologic, hydraulic, and other pertinent data used in this
study can be obtained by contacting the Natural and Technological
Hazards Division, Federal Emergency Management Agency, Denver Federal
Center, Building 710, Denver, Colorado 80225.
8.0 BIBLIOGRAPHY AND REFERENCES
1. U.S. Department of Commerce, Bureau of the Census, "1980 Census of
Population, Number of Inhabitants, Colorado," 1981
2. U.S. Department of Commerce , National Climatic Center ,
Climatological Data for Colorado, Annual Summary 1976, Asheville,
North Carolina, 1977
3. U.S. Department of Agriculture, Soil Conservation Service, General
Soil Map for Weld County, Colorado, Scale 1:10,560, May 1972
4. U.S. Department of the Army, Corps of Engineers, Omaha District,
Flood Plain Information Report, Cache La Poudre River, Colorado,
Volume II, Greeley-Weld County, Scale 1:12,000, March 1974
5. , Special Flood Hazard Information Report, South
Platte River, Volume I, Weld County, Colorado, prepared for Weld
County and Colorado Water Conservation Board, April 1977
6. U.S. Department of Agriculture, Soil Conservation Service,
Engineering Division, Technical Release No. 20, Computer Program
for Project Formulation, May 1965
40
7. U.S. Department of the Interior, Geological Survey, 7.5-Minute
Series Topographic Maps, Scale 1:24,000, Contour Interval 10 feet:
Bracewell, Colorado (1950), Photorevised (1969)
8. U.S. Department of Commerce, National Oceanic and Atmospheric
Administration, Precipitation-Frequency Atlas of the Western United
States, NOAA Atlas 2, Colorado, 1973
9. U.S. Department of Agriculture, Soil Conservation Service, National
Engineering Handbook, Section 4, August 1972
10. U.S. Department of the Interior, Geological Survey, 7.5-Minute
Series Topographic Maps, Scale 1:24,000, Contour Interval 10 feet:
Milliken, Colorado (1950), Photorevised (1969)
11. , 7 .5-Minute Series Topographic Maps, Scale
1:24,000, Contour Interval 10 feet: Eaton, Colorado (1950),
Photorevised (1971)
12. U.S. Department of Agriculture, Soil Conservation Service, Flood
Hazard Analyses, Coal Creek and Rock Creek, Boulder and Weld
Counties, Colorado, October 1976
13. U.S. Department of Agriculture, Soil Conservation Service, National
Engineering Handbook, Hydrology, Section 4, August 1972
14. , Engineering Division, Central Technical Unit,
Technical Release No. 20, Computer Program for Project Formulation,
May 1965
15. U.S. Department of the Army, Corps of Engineers, Hydrologic
Engineering Center, HEC-2 Water-Surface Profiles, 723-X6-L202A,
Davis, California (Revised February 1977)
16. Nelson, Haley, Patterson 6 Quirk, Inc. , Preliminary Engineering
Report, Drainage Study, Firestone-Frederick Area, Weld County,
Colorado, Scale 1:24,000, Contour Interval 1 foot, September 1975
17. Weld County and Colorado Water Conservation Board, Aerial
Photogrammetric Maps for Sheep Draw Flood Plain Study, Scale
1:2,400, Contour Interval 2 feet, prepared by M and I Consulting
Engineers, Fort Collins, Colorado, December 1978
18. Water Resources Consultants, Inc. , Topographic Maps, Coal Creek,
Boulder and Weld Counties, Colorado, compiled by photogrammetric
methods, Scale 1:4,800, Contour Interval 2 and 4 feet: February
1980
19. Water Resources Consultants, Inc. , Floodplain Information, Flood
Control and Floodplain Management Plan for Coal Creek at Erie,
Colorado, and Technical Addendum, August 1980
41
20. U.S. Department of the Army, Corps of Engineers, Omaha District,
Flood Plain Information Report, Big Thompson River, Weld County,
Colorado, Scale 1:6,000, February 1978
21. U.S. Department of the Interior, Geological Survey, 7.5—Minute
Series Topographic Maps, Scale 1:24,000, Contour Interval 10 feet;
Greeley, Colorado (1950), Photorevised (1969); LaSalle, Colorado
(1951); Fort Lupton, Colorado (1949), Photorevised (1969)
22. U.S. Department of the Army, Corps of Engineers, Omaha District,
Flood Plain Information, Cache La Poudre River, Colorado, Volume
III, Fort Collins - Greeley, Larimer - Weld County, Colorado, Scale
1:12,000, October 1975
23. U.S. Department of the Interior, Geological Survey, 7.5-Minute
Series Topographic Maps, Scale 1:24,000, Contour Interval 10 feet:
Platteville, Colorado (1950), Photorevised (1969); Kersey, Colorado
(1950); Barnesville, Colorado (1950); Hardin, Colorado (1950);
Dearfield, Colorado (1951); Masters, Colorado (1950)
24. U.S. Department of the Interior, Geological Survey, 7.5-Minute
Series Topographic Maps, Scale 1:24,000, Contour-Interval 10 feet:
Hereford, Colorado (1972)
25. Weld County and Colorado Water Conservation Board, Topographic
Mapping of Idaho Creek, Flown April 25, 1977, Scale 1:24,000,
Contour Interval 2 feet, prepared by Kucera & Associates, Inc. ,
Denver, Colorado
26. Federal Emergency Management Agency, Flood Hazard Boundary Maps,
Weld County, Colorado, Scale 1:2,000, March 1978
27. , Flood Insurance Study, City of Greeley, Colorado,
prepared by Gingery Associates, Inc. , December 1977
28. , Flood Insurance Study, City of Evans, Colorado,
prepared by Gingery Associates, Inc. , October 1977
�9. , Flood Insurance Study, City of Fort Lupton,
Colorado, prepared by Gingery Associates, Inc. , October 1977
30. , Flood Insurance Study, Town of Frederick,
Colorado, prepared by Gingery Associates, Inc. , unpublished
31. , Flood Insurance Study, Town of Firestone,
Colorado, prepared by Gingery Associates, Inc. , unpublished
32. , Flood Insurance Study, Town of Dacono, Colorado,
prepared by Gingery Associates, Inc. , unpublished
33. Federal Emergency Management Agency, Flood Insurance Study, Town of
Erie, Colorado, prepared by Gingery Associates, Inc. , June 1977
42
34. , Flood Insurance Study, Town of Milliken, Colorado,
prepared by Gingery Associates, Inc. , October 1977
35. , Flood Insurance Study, Town of Windsor, Colorado,
prepared by Gingery Associates, Inc. , December 1977
36. , Flood Insurance Study, Town of Nunn, Colorado,
prepared by Gingery Associates, Inc. , October 1977
37. , Flood Insurance Study, Town of Pierce, Colorado,
prepared by Gingery Associates, Inc. , November 1977
38. Federal Emergency Management Agency, Federal Insurance
Administration, Flood Insurance Study, Town of Erie, Colorado,
September 1982
39. Hydrologic Analysis of the Cache La Poudre Basin. Engineering
Division Technical Report; U.S. Army Corps of Engineers, Omaha
District, April 1988
40. U.S. Department of the Army, Corps of Engineers, Hydrologic
Engineering Center, HEC-1 Flood Hydrograph Package, Davis ,
California, January 1973
41. HEC-2 Water Surface Profiles, Generalized Computer Program. U.S.
Army Corps of Engineers, Hydrologic Engineering Center, Davis,
California, September 1982
42. Open Channel Hydraulics. Chow, V.T. , McGraw-Hill Book Company,
Inc. , New York, New York, 1959.
43. Colorado Water Conservation Board, topographic mapping, scale
1:2,400, contour interval 4' , date unknown.
43
9.0 REVISIONS DESCRIPTION
This section has been added to provide information regarding significant
revisions made since the original Flood Insurance Study was printed. Future
revisions may be made that do not result in the republishing of the Flood
Insurance Study report. To assure that any user is aware of all revisions,
it is advisable to contact the community repository.
9.1 First Revision
The purpose of this revision is to add flooding information from
the Cache La Poudre River near the Town of Windsor that affects the
unincorporated areas of Weld County.
The hydrologic flood frequency relationships used in the study were
prepared by the COE, Omaha District (Reference 39).
The hydraulic analysis for this study was prepared by Simons, Li &
Associates, Inc. , the study contractor, for FEMA under Contract
Number EMW-86-C-2262. This work was completed in July 1990.
An initial coordination meeting for this study was held between
representatives of Weld County, the Town of Windsor, FEMA, the
CWCB, and the study contractor on March 30, 1988. The primary
purpose of this meeting was to discuss the study limits for the
detailed analysis, the hydrology, historic flooding problems ,
structures located within the study reach, the availability of
suitable mapping, and issues regarding the Eastman Kodak Company
(Kodak), which owns property and has a manufacturing plant adjacent
to the Cache La Poudre River.
On July 6, 1989, a intermediate Consultation and Coordination
Officer's (CCO) meeting was held at the study contractor' s office
with representatives of FEMA, the Town of Windsor, and the study
contractor. Preliminary results of the floodplain analysis in Weld
County were reviewed and discussed.
The results of this study were reviewed at the final CCO meeting
held on December 13, 1990, and attended by representatives of Weld
County, the Town of Windsor, the study contractor, and FEMA. All
problems raised at that meeting have been resolved.
The Cache La Poudre River was studied by detailed methods from Weld
County Road 23 upstream to the Larimer/Weld County boundary, a
distance of 9.3 river miles.
The COE hydrology was developed using HEC-1, a general rainfall-
runoff computer model developed by the COE' s Hydrologic Engineering
Center (Reference 40). The appropriateness of this routing method
was verified using historical data for the 1976 and 1983 floods on
the Cache La Poudre River. The HEC-1 routing method is considered
valid to use for the routing of the hypothetical 100—year flood
(Reference 39). The results of the COE hydrologic analysis were
44
reviewed and accepted by the Town of Windsor, FEMA, and the CWCB.
Results of the COE hydrology analysis are shown in Summary of
Discharges (Table 1).
Cross-sectional data, including overbanks, for the backwater
analyses were obtained by field survey. All bridges were surveyed
to obtain elevation data and structural geometry. The land-use and
hydraulic-roughness data were also obtained by field surveys.
Water-surface elevations for floods of the selected recurrence
intervals were computed using the COE HEC-2 step-backwater program
(Reference 41). Starting water-surface elevations for the Cache La
Poudre River were determined by normal depth calculations.
Channel and overbank hydraulic roughness factors (Manning's "n")
used in the hydraulic computations were determined using
engineering judgment and were based on field observations of the
stream and floodplain areas and the descriptions presented in
standard engineering references (Reference 42). The channel "n"
value for the Cache La Poudre River was estimated as 0.035
throughout the study reach, and the overbank "n" values ranged from
0.043 to 0.110. The hydraulic analyses for this study were based on
unobstructed flow. All computed water-surface elevations are
referenced to the NGVD of 1929.
Four locations of divided flow were identified within the study
reach; at the Larimer/Weld county boundary, at Weld County Road 17,
at Colorado State Highway 257, and at the Kodak and Windsor
wastewater treatment plants. Each of these divided flow paths were
modeled separately using HEC-2.
Floodplain boundaries were delineated using topographic maps at a
scale of 1:2,400 with a contour interval of 4 feet. These maps
were provided by the CWCB solely for mapping purposes (Reference
43). The date of the mapping is unknown. The hydraulic analysis
for the Cache La Poudre River in Weld County was based on surveyed
cross-sectional data. In locations where the contours on the
mapping do not agree with surveyed data, the floodplain was mapped
according to the surveyed data.
Computation of portions of the floodway in the study reach required
nonstandard solutions due to the numerous divided flow paths. In
location of divided flow, it was attempted to channel all of the
flow into the mainstem path, limiting the flow to the 100-year
floodplain. If the water-surface elevation increase was less than
the allowable surcharge, the main flow path was encroached by
proportional conveyance reduction. If the water-surface elevation
increase caused by the additional discharge was greater than the
allowable surcharge, then water was allowed to flow both along the
main flow path and the involved divided flow paths. The divided
flow paths were then encroached using proportional conveyance
reduction until the allowable surcharge was reached. The floodway
was then defined as the outer limits of the two paths.
45
In areas where divided Clow paths were not present, the Iloodwny
was computed using proportional conveyance reduction from each side
of the floodplain with adjustments as necessary to obtain a
consistent and reasonable floodway. Refer to Table 2 for Floodway
Data.
46
Hello